Add aerial perspective to fixed fog

3 files changed, 28 insertions, 10 deletions

diff --git a/servers/rendering/rasterizer_rd/shaders/scene_high_end.glsl b/servers/rendering/rasterizer_rd/shaders/scene_high_end.glsl
index be34473892..ec199c0d0e 100644
--- a/servers/rendering/rasterizer_rd/shaders/scene_high_end.glsl
+++ b/servers/rendering/rasterizer_rd/shaders/scene_high_end.glsl
@@ -1621,6 +1621,22 @@ vec4 volumetric_fog_process(vec2 screen_uv, float z) {
 vec4 fog_process(vec3 vertex) {
 	vec3 fog_color = scene_data.fog_light_color;
 
+	if (scene_data.fog_aerial_perspective > 0.0) {
+		vec3 sky_fog_color = vec3(0.0);
+		vec3 cube_view = scene_data.radiance_inverse_xform * vertex;
+		// mip_level always reads from the second mipmap and higher so the fog is always slightly blurred
+		float mip_level = mix(1.0 / MAX_ROUGHNESS_LOD, 1.0, 1.0 - (abs(vertex.z) - scene_data.z_near) / (scene_data.z_far - scene_data.z_near));
+#ifdef USE_RADIANCE_CUBEMAP_ARRAY
+		float lod, blend;
+		blend = modf(mip_level * MAX_ROUGHNESS_LOD, lod);
+		sky_fog_color = texture(samplerCubeArray(radiance_cubemap, material_samplers[SAMPLER_LINEAR_WITH_MIPMAPS_CLAMP]), vec4(cube_view, lod)).rgb;
+		sky_fog_color = mix(sky_fog_color, texture(samplerCubeArray(radiance_cubemap, material_samplers[SAMPLER_LINEAR_WITH_MIPMAPS_CLAMP]), vec4(cube_view, lod + 1)).rgb, blend);
+#else
+		sky_fog_color = textureLod(samplerCube(radiance_cubemap, material_samplers[SAMPLER_LINEAR_WITH_MIPMAPS_CLAMP]), cube_view, mip_level * MAX_ROUGHNESS_LOD).rgb;
+#endif //USE_RADIANCE_CUBEMAP_ARRAY
+		fog_color = mix(fog_color, sky_fog_color, scene_data.fog_aerial_perspective);
+	}
+
 	if (scene_data.fog_sun_scatter > 0.001) {
 		vec4 sun_scatter = vec4(0.0);
 		float sun_total = 0.0;
diff --git a/servers/rendering/rasterizer_rd/shaders/scene_high_end_inc.glsl b/servers/rendering/rasterizer_rd/shaders/scene_high_end_inc.glsl
index 0cc2b90c53..e29a490ca1 100644
--- a/servers/rendering/rasterizer_rd/shaders/scene_high_end_inc.glsl
+++ b/servers/rendering/rasterizer_rd/shaders/scene_high_end_inc.glsl
@@ -43,12 +43,6 @@ layout(set = 0, binding = 3, std140) uniform SceneData {
 	vec2 viewport_size;
 	vec2 screen_pixel_size;
 
-	float time;
-	float reflection_multiplier; // one normally, zero when rendering reflections
-
-	bool pancake_shadows;
-	uint pad;
-
 	//use vec4s because std140 doesnt play nice with vec2s, z and w are wasted
 	vec4 directional_penumbra_shadow_kernel[32];
 	vec4 directional_soft_shadow_kernel[32];
@@ -108,6 +102,13 @@ layout(set = 0, binding = 3, std140) uniform SceneData {
 
 	vec3 fog_light_color;
 	float fog_sun_scatter;
+
+	float fog_aerial_perspective;
+
+	float time;
+	float reflection_multiplier; // one normally, zero when rendering reflections
+
+	bool pancake_shadows;
 }
 
 scene_data;
diff --git a/servers/rendering/rasterizer_rd/shaders/sky.glsl b/servers/rendering/rasterizer_rd/shaders/sky.glsl
index 7711f683ae..f1a31d3486 100644
--- a/servers/rendering/rasterizer_rd/shaders/sky.glsl
+++ b/servers/rendering/rasterizer_rd/shaders/sky.glsl
@@ -62,7 +62,8 @@ layout(set = 0, binding = 2, std140) uniform SceneData {
 	bool volumetric_fog_enabled;
 	float volumetric_fog_inv_length;
 	float volumetric_fog_detail_spread;
-	uint volumetric_fog_pad;
+
+	float fog_aerial_perspective;
 
 	vec3 fog_light_color;
 	float fog_sun_scatter;
@@ -140,8 +141,8 @@ vec4 volumetric_fog_process(vec2 screen_uv) {
 	return texture(sampler3D(volumetric_fog_texture, material_samplers[SAMPLER_LINEAR_CLAMP]), fog_pos);
 }
 
-vec4 fog_process(vec3 view) {
-	vec3 fog_color = scene_data.fog_light_color;
+vec4 fog_process(vec3 view, vec3 sky_color) {
+	vec3 fog_color = mix(scene_data.fog_light_color, sky_color, scene_data.fog_aerial_perspective);
 
 	if (scene_data.fog_sun_scatter > 0.001) {
 		vec4 sun_scatter = vec4(0.0);
@@ -225,7 +226,7 @@ FRAGMENT_SHADER_CODE
 
 	// Draw "fixed" fog before volumetric fog to ensure volumetric fog can appear in front of the sky.
 	if (scene_data.fog_enabled) {
-		vec4 fog = fog_process(cube_normal);
+		vec4 fog = fog_process(cube_normal, frag_color.rgb);
 		frag_color.rgb = mix(frag_color.rgb, fog.rgb, fog.a);
 	}